Abstract
The defect structure of CeO
2−
x
has been investigated over the composition range from CeO
2 to CeO
1.8 and 900°C using the combined techniques of high temperature dilatometric length change and X-ray lattice parameter measurements. The oxygen partial pressure associated with the nonstoichiometric composition was controlled by passing different ratios of H
2/He mixtures through a constant temperature water bubbler and was monitored constantly with a YSZ oxygen sensor. The difference between the percent expansion for the dilatometric and X-ray lattice parameter measurements was zero, which indicated that the predominant defects of the CeO
2-
x
are oxygen vacancies.